Dysbiosis, gut–blood barrier rupture and autoimmune response in rheumatoid arthritis and schizophrenia

The primary cause of chronic autoimmune diseases is elusive both in somatic medicine and psychiatry. Examples of such conditions are rheumatoid arthritis and schizophrenic disorders. Immune disturbances occur in both diseases, but it is difficult to combine them into a meaningful pathogenetic model. The immunological hypothesis of schizophrenia is based on non-specific changes in the cytokine system and exponents of chronic inflammation in some patients. In rheumatoid arthritis the cytokine network is much better known than in schizophrenia, and interleukin-6, tumor necrosis factor or Janus kinases became a target of treatment. Microbiome dysbiosis and disturbances of the blood–gut barrier may be a new hypothesis of the pathogenesis of somatic and psychiatric diseases. The purpose of this narrative review was to show, using the example of two chronic diseases – rheumatoid arthritis and schizophrenic disorders – that disturbances in the blood barrier of the intestine can be a common mechanism of somatic and mental disorders. The paper presents the current state of knowledge on the hypothetical relationship between microbiome dysbiosis and the pathogenesis of schizophrenia and rheumatoid arthritis. In conclusion, in the light of discoveries regarding the microbiome–gut–brain axis the immunological model of rheumatoid arthritis and schizophrenia formation may gain importance and contribute to the creation of new strategies for causal treatment of these still incurable diseases.